High Temperature exhaust gases from both turbine and piston engines are sometimes unavoidably close to parts of the airframe. Tailpipes and mufflers contain the flame but the convective heat can be too much for the surrounding balsa, plastic, or fiberglass structures.
Two to three brushed on coats of this water based, ceramic material, "Heat Shield" will protect those exposed parts of your model. Simply treat the inside of the engine cowl (piston engines) or the inside of the aft fuselage (turbine) and the surface temperature of the model will remain cool. In the unusual case of a turbine tailpipe fire on start up, you will have several seconds longer to extinguish it before any damage to the model occurs.
Heat Shield comes in a 8oz can and is easily applied with a brush, clean up with soapy water. For extra protection the thickness can be built up with additional layers of fiberglass cloth and Heat Shield.